Determination of Hysteresis Controller Band for IPMSM-Based Drive System

Abstract

Methods of providing a control band for a hysteresis controller are presented. A method can determine a control band analytically to avoid the time and costs associated with manual calibration of a hysteresis controller. By way of example, a method can include modeling a machine output, such as stator flux or machine torque, modeling the variation rate for the machine output, and providing a control band based on the variation rate modeling.

Description

FIELD OF INVENTION[0001]This invention relates generally to direct torque control (DTC) for an electric machine (IPMSM), and more particularly to a method for determining a DTC hysteresis controller band.BACKGROUND[0002]The demand for electric and hybrid electric vehicles continues to grow as governmental agencies, private organizations and individual consumers strive to conserve resources, reduce energy costs and lower carbon emissions. Electrified vehicles have an electric drive system that includes an electrical machine to assist or replace the internal combustion engine of a conventional vehicle, a power conversion system configured to provide energy to the electric machine, and a machine controller configured to control machine operation. Due to its high power / torque density, its high efficiency, and its high reliability, a permanent magnet synchronous motor (PMSM) is a popular choice for electric vehicle drive systems. Most machine controllers used with PMSMs in electric vehic...

AI Technical Summary

Benefits of technology

The patent text describes a method for determining the band for a hysteresis controller in an electric drive system of a vehicle. The method involves modeling the machine output, the variation rate of the output, and the band of the controller based on these models. The band can be determined based on the maximum switching frequency of the inverter or the maximum torque of the machine. The method can be implemented using a processor and computer-readable media. The technical effect of the patent is to provide a more accurate and efficient way to control the hysteresis in an electric drive system.

Problems solved by technology

However, FOC systems can be rather complex, requiring continuous rotor position information, current regulators, transformations between rotating and stationary coordinate systems, and pulse width modulation (PWM) generators.

While small bands may be desired for higher machine output accuracy, they are generally not achievable given the physical limitations of drive system components.

On the other hand, large bands, more easily achievable, are prone to noise, vibration and harshness problems which can adversely impact performance and disappoint and / or frustrate an operator.

Unfortunately, there is no universal or standard method for specifying hysteresis controller bands for a particular application.

Instead, determination of controller bands is essentially a trial and error process which can be costly and inefficient.

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